Understairs Cupboard

Finding enough storage space in a home is one of the ultimate challenges in pretty much everyone’s life. The average home just doesn’t have enough storage space and we all tend to collect way too much stuff to fit in what little there is. Finding every possible bit of unused space and turning it into something useful can end up becoming somewhat of a quest.

Perhaps one of the most underutilized potential storage spaces in most homes is the space under the stairs. While some home designs might fit a coat closet under the stairs, even that is done in a way that doesn’t make efficient use of the space, wasting much of it. Other homes don’t even bother with this, just closing the space off in the name of cost containment and design.

Yet adding an understairs cupboard can put a considerable amount of highly usable storage right where it’s needed. Those stairs are often located close to the entryway, meaning they are right where family members are looking to put things down, when they come in the door.

Coming up with a Workable Design

What kind of understair cupboard is installed in any particular type of home depends a lot on the way the home is built; specifically, how the stairs are built and where that might leave a wall that can be cut through to gain access to the space under the stairs. There are three basic stair designs, each of which has its own potential design advantages.

  • Straight stairs – Offers the largest amount of space on a single wall, with the greatest height. Great for cascading shelves or cabinets forming a wedge shaped design. 
  • Right angle stairs – The big advantage of staircases forming a right angle is the landing space that isn’t available under straight stairs. This area provides the opportunity for a large square cabinet area, while still leaving space under both the upper and lower staircases to use.
  • Switchback stairs – If angled stairs are good because of the space under the landing, then switchback stairs are twice as good, because there’s twice as much space under the landing; enough space to build a playroom for small children.

The other factor here is which side of the staircase the understair cupboard or cupboards are going to be installed from. Installing from the direction of the upper floor landing provides the most headroom, which is necessary for a coat closet, but it doesn’t give as much in the way of width. Coming at the staircase from the side will provide lots of width, especially under a straight staircase. But if the idea is to utilize the space under a landing, it might actually be best to work from the back side of the stairs, if they are accessible.

Of course, the room that these new cabinets would open onto is part of the equation as well. Storage opening up onto the home’s entryway or living room is likely to be used considerably differently than storage into the kitchen. I had an understairs cabinet in one home which was so deep, that I made a pull-out cart to go into it, which we used for storing all the kitchen appliances on.

Don’t dismiss the possibility of putting understairs cupboards in more than one room either; especially in cases where right angle stairs or switchback stairs are installed in the home. It may not be possible to access all the space from one side, necessitating multiple cabinets, accessing the space from multiple rooms.

Start by Framing the Area

Regardless of the design used, the first part of the project is to open up the space under the stairs and then framing it in. This space is typically covered by drywall, which is attached to a 2”x 4” framework, hiding the spandrel (the technical name for this space).

However, this 2”x 4” framework is not load-bearing. It’s not holding up the stairs in any way. Staircase stringers, the 2”x 12” angled boards on either side of the stairs are what hold them up. These are attached to the header at the top of the stairs and sit on the floor at the bottom. All the 2”x 4” framework is there for is to support the drywall.

So, since this structure is not providing any structural support, it can be removed. Actually, we don’t want to remove it; we want to cut it off flush with the bottom of the stringer, as well as cutting it on the sides, so that the understair cabinet will fit in place.

Start by finding the edge of the stair stringer. There are several ways of doing this, but the easiest is to make a couple of holes a couple of inches away from the Lowest point where the stringer could be, then cutting upwards from there to find the stringer. Once that point is found in two separate places, it’s a simple matter to use those points as a frame of reference to draw a cut line, at the bottom of the stringer. The vertical lines on either end are more a matter of choice, depending on the design of the cabinetry.

With the drywall removed, cut off the 2”x 4” studs at an angle, flush with the bottom of the stringer. These are still needed, so as to support the drywall above and to either side of the new cabinetry. Fill the open spaces between these studs with pieces of the removed 2”x 4”, cut at an angle to fit.

In addition to the structure above the new cabinetry, there is also a need to have at least a little bit on either side. If there are not 2”x 4”s already framing this area, then add them in, so that there is something to nail the cabinet insert into, as well as the door casing that will join the new insert to the rest of the wall. Once these are in place, cut off the floor plate flush with the edge of the studs and attach the drywall to the framework.

A Simple Storage Space

A simple cupboard can be made in the space under the stairs simply by finish it out and adding a doorway. In this case, the width of the opening that is made (as discussed above) might not be the full width of the area available. However, it needs to be wide enough, so that whatever is going to be stored underneath the stairs can fit through the door.

While many people forgo finish out this area, leaving the studs exposed, it’s really not all that hard to install drywall and finish it, making the space look much more finished. Rather than using drywall right around the opening, it’s a good idea to use dimensional boards, as they are stronger and will resist damage much better than the drywall will.

In this case, once the inside of the area is finished, all that needs to be done is to add a door or two. There are door kits manufactured, specially designed for installing an understair cabinet. The other option is to have custom made doors from any kitchen cabinet door manufacturer.

understairs cupboard
Understairs cupboard, Henry Burrows

Built-in Cabinet

Most people opt for a more comprehensive design, giving them customized storage space. It doesn’t matter if they’re trying to create bookshelves, drawers or cubbyhole; the basic construction remains the same. That is, to create a cabinet insert which can be installed directly into the space that has been opened up, under the stairs.

Before making the insert, check the floor for level in both directions and the walls for plumb. Building code allows for the floor and walls to be slightly off when the home is built and time will only make that worse. Knowing about any such irregularities first makes it easier to size the insert so that there won’t be any problems fitting it in. In order to make room for these irregularities, make the insert slightly smaller than the opening. It can then be shimmed when installed.

It’s best to start the insert by making the cabinet facing, rather than making the cabinet itself. Ultimately, the facing is the part that everyone is going to see, so it needs to look good and fit well into the opening. With a good facing, the chances of making a cabinet insert which will fit are much better.

Cut the various pieces of the facing necessary out of hardwood dimensional lumber. There will be some unusual angles to this, especially at the top, as the insert will not be square. Take care to measure and cut the angles carefully, so as to obtain snug joints.

Before gluing and screwing the cabinet face frame tighter, dry clamp it together, to ensure that everything fits properly. Due to the complexity, it may be necessary to assemble it in stages, gluing and screwing each section together, then allowing the glue to set, with the parts clamped together. This is an ideal place for the use of pocket screws from the back. They will provide the most possible strength, while not leaving hole in the surface like finish nails would. Besides, many of these connections will be into end grain, which doesn’t glue well.

Once the cabinet face frame is complete, set it in the opening under the stairs to check for fit.

The perimeter of the cabinet insert should be made of plywood. Parts which will be visible when cabinets are opened should be made out of hardwood plywood. However, the plywood should be installed with the face grain inside, rather than outside, as that will be the only side visible. Pieces which will not be visible, because of being covered up by drawers don’t need to be made of cabinet grade plywood, but can be made of normal construction-grade plywood. Again, put the face side to the inside.

The back of the cabinet will be covered with ¼” thick plywood, again putting the face grain to the inside of the cabinet insert. But before installing it, all other dividers need to be installed. These can be attached by nailing through the outer casing, into the edges of the plywood dividers. In cases where the divider is a shelf that will be supporting weight, more than nails should be used. Glue and nail a strip of ¾” square lumber, ripped from a 1”x 4” board, to the sides of the case and/or dividers to support the shelf.

Adding strips like this may be necessary in other parts of the casing, such as attaching corners together. Ideally, the insert should be strong enough that it can be moved about, without any risk of becoming wobbly or breaking. Adding these strips can make joints, especially corner joints, considerably stronger.

Installing the Insert

The finished insert should slip neatly into the opening created under the stairs. The big question will be whether the cabinet facing will fit flush with the wall, all the way around. If it doesn’t this indicates the need for shimming. For example, if the bottom is flush, but the top is protruding by ¼”, this indicates that the floor is uneven and the cabinet insert is tipping forward. Adding door shims under the front edge will quickly cure this problem, making the cabinet insert fit evenly all the way around.

Shims should also be installed in places where there is a gap, even if there is no unevenness. Placing two shims on top of each other, facing in opposite directions, allows the shims to be adjusted so that the outer surfaces are parallel and they fill the gap snugly.

Nail through all the sides, into the adjacent wood. Always be sure to nail through any shims, to keep them from moving. After nailing, cut off the excess shim with a utility knife.

To finish out the installation, use the door and window casing to cover the crack between the cabinet insert and the wall around it. The 2”x 4” framing installed earlier provides good backing to nail to. Use 8d finish nails to attach the thicker part of the casing to structure, through the plywood and 4d finish nails to nail through the thin end of the casing to the insert’s face frame. Corners must be mitered, which will be a bit of a challenge, as they are going to be at unusual angles.

To miter these corner, measure them accurately. Then divide that in half. This is the angle to set on the miter saw, in order to get a true miter. After cutting the miter, it’s a good idea to sand the adjoining surface in a way so that it has a negative relief (so that the face edge sticks out farther). This will allow the joint to be pushed together, even if the cut isn’t perfect, hiding any imperfection.

The final step is to install the doors and drawers. It’s best to wait until the unit is installed for this, so as to keep the weight of the insert down. It also allows for minor positional adjustments, if things turn out to be slightly out of square.

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